The invention relates to a wheel bearing which is disposed between a knuckle arm of a vehicle or the like and a driven wheel, and particularly to a wheel bearing which can prevent a flange of a hub attached to a wheel from being deformed and reduce the weight of the hub.
A wheel bearing such as shown in FIG. 4 is disposed between a knuckle arm and a wheel. The wheel bearing comprises: a hub 21 which is fixed to the side of a wheel; inner race members 24 and 25 which are fittedly fixed to a shaft body 21a of the hub 21; an outer race 22 which is fixed to the side of a vehicle body; balls 23 which are arranged between the hub 21 and the outer race 22; a nut 26 which fixes the inner race members 24 and 25 to the shaft body of the hub 21; and a seal member 27.
In the thus configured wheel bearing, the hub 21 is fixed at a flange 21f to the side of the wheel (not shown), and the outer race 22 is fixed at a flange 22f to the side of the vehicle body (not shown). The outer peripheral face 21b of the shaft body 21a of the hub 21, and the side face 21g of the flange 21f must be accurately worked. The nut 26 is fastened by using a dog 28 which is disposed on the inner side of an annular portion 21c that is at the root of the flange 21f of the hub 21 and in a side opposite to the shaft body 21a. However, the dog 28 interferes with the operation of working the hub 21, thereby making the working operation difficult to conduct. To comply with this, the hub 21 is worked in the following manner. As shown in FIG. 5, holes 21h and 21i are formed in both the sides of the center of the hub 21, and, while supporting the hub 21 by center jigs 30 and 31, a side face 21g of the flange 21f and the outer surface 21b of the shaft body 21a are machined. While the hub 21 is supported at the holes 21h and 21i by the center jigs 30 and 31, thereafter, the shaft body 21a is rotated via the dog 28 and the side face 21g of the flange 21f is polished. The outer surface 21b of the shaft body 21a is then polished by using a backing plate 32 and a shoe 33 with using the flange 21f as a reference. In the case where the holes 21h and 21i are axially misaligned with each other, when only the machining process is conducted, a desired accuracy may not be attained. The polishing processes are employed in order to improve the accuracy in such a case.
As described above, in the wheel bearing of the prior art, different jigs such as the center jigs 30 and 31, and the backing plate 32 and the shoe 33 are required in the processes of polishing the side face 21g of the flange 21f of the hub 21, and the outer peripheral face 21b of the shaft body 21a.
Therefore, the work is relatively cumbersome. In the case where the nut 26 is to be screwed and fastened, there is a problem in that, when the nut 26 is fixed by using the dog 28 as a rotation locking member, the flange 21f is easily deformed. Moreover, there is a further problem in that the formation of the dog 28 in the axial center area of the hub 21 increases the weight of the hub 21.